Paediatric Auto Renal transplantation-Anaesthetic Challenge.

SUMMARY
Takayasu's arteritis is described to be the single most important cause of renovascular hypertension. Anaesthetising a child with Takayasu's arteritis for auto renal transplantation is a challenge as it is complicated by severe uncontrolled hypertension, end-organ dysfunction resulting from hypertension, stenosis of major blood vessels affecting regional circulation, and difficulties encountered in monitoring arterial blood pressure. A balanced anaesthetic technique, maintenance of stable haemodynamics with monitoring is required for a successful outcome. We describe the anaesthetic management of a child with Takayasu's arteritis and severe hypertension refractory to medical treatment requiring auto renal transplantation.


Introduction
Severe persistent hypertension in childhood is mainly dueto renalparenchymal diseasewith renovascular lesions being the second most common cause. Takayasu's arteritis is the single most important cause of renovascular hypertension in non white children 1 . Takayasu's arteritis is characterized by a focal stenosis process involving the aorta and the proximal segment of its major branches 2 . We present the anaesthetic management of a child with Takayasu's arteritis and severehypertension refractoryto medicaltreatment requiring auto renal transplantation.

Case report
A 4-year-old male child weighing 13 kg, presented with history ofdyspnoea on exertion for 3month duration. On examination, all peripheral pulses were palpable except on theright upperlimb. His blood pressure was 140/100 mm Hg in the left upper limb and was not recordable on the right upper limb. He was evaluated for secondary hypertensionand foundto have Type III Takayasu's arteritis with aortography revealing 99% stenosis of left main renal artery and 60% stenosis of the right main renal artery as wellas occlusion of the right subclavian artery (Fig1). He had clinicaland echocardiographic evidence of left ventricular dysfunction withnormal renalfunctions. He was stabilized on tab.nifedepine 5mg Q4H, prazosin1mg Q6H, aldomet250mgQ8H, minoxidil 5mgQ12H, frusemide 10 mg, digoxin 0.25 mg and aspirin once a day. He underwent balloon angioplasty and stenting ofleft renal artery. He presented subsequently with a history of recurrentepisodes of seizures and persistently elevated blood pressure. MRI brain revealed vasculitis induced multiple infarcts. Right auto renaltransplantation was considered due to refractory hypertension and ongoing complication. Preoperative vitals revealed GCS of 14/15, heart rate of 96/min, absent right radial pulse with blood pressurein left upper limb of 170/110mmHg. His blood investigations were normal with serum creatinine of 0.9mg%. Chest roentgenogram revealed cardiomegaly and electrocardiogram left ventricular hypertrophy.
The patient was fasted and premedicated with Syp.Triclofos 75mg.kg -1 . Under standard monitoring (SpO 2 , non-invasive blood pressure, ECG, end-tidal CO 2 monitor, temperature), anaesthesia was induced with air, oxygen and sevoflurane. The trachea was intubated following atracurium administration and the patient mechanicallyventilated. Underultrasound guidance, a 5F triple lumen catheter was sited in the right internal jugular vein. The left femoral artery was selected for direct arterial pressure monitoring. Anaesthesia was maintained with 50 % mixture of air and oxygen, end-tidal isoflurane concentration of 1% with morphine, fentanyl and atracurium boluses as needed. Normocarbia was maintained to preserve cerebral perfusion. Surgery was done in supine position. A good perfusion pressure of the transplanted kidney was ensured by maintaining a systolic blood pressure of 130 mm Hg, CVP of 13-15 mmHg. Mannitol 0.5g.kg -1 was infused 20 minutes before clamp release. Blood loss wasreplaced with fresh whole blood. Urine output was more than 0.5 ml.kg -1 .hr -1 after the anastamosis. The intraoperative period wasuneventful.Arterialblood gas analysis waswithin normallimits andtrachea extubated at the end of the procedure. Post operatively, the child was monitored in the high dependencyunit and had an unremarkable stay.Outpatient visit at 8weeks revealed improved sensorium and blood pressure of 130 / 85mmHg in left upperlimb. Diethylene Tetramine Penta Acetate(DTPA) scan done at 8 weeks showed functioning of auto transplanted kidney (Fig 2) and antihypertensives were tapered. Colour doppler re-vealed good perfusion of transplanted kidney as characterized by the reduction in the peaksystolic velocity from 244.1 cm/sec to 120.5 cm/sec. (Fig 3) F ig 2 D TPA sc an revea ling upt ake by a ut o transplanted kidney on right side.

Discussion
Patients with Takayasu's arteritis (TA) present for surgery either incidentally or more frequently for correction of the consequences of vascular occlusive disease.Anaesthetising such a child for auto renal transplantation is a challenge as it is complicated by severe uncontrolled hypertension, end-organ dysfunction resulting from hypertension, stenosis of major blood vesselsaffectingregionalcirculation, anddifficulties encountered in monitoring arterial blood pressure 3 . Surgery is indicated in patients withuncontrolled hypertension, deteriorating renal function, lesions not amenable to angioplasty and transient response to angioplasty 4 . In our patient, auto renal transplantation was resorted to as he was not responding to antihypertensives and stenting of the stenosed left renal artery. Regional analgesia with epidural was not initiated in our patient as the risk of decrease in blood pressuremay be hazardous in a patient withcompromised regionalcirculation because of stenosed arteries 5, 6 . This haemodynamic instability can also result inreduced graft function 7 .We used isoflurane to maintain the blood pressure at basal preoperative levels, decrease the cerebral metabolic rate of oxygen and produce cerebral vasodilatation.
Sudden hypertensive or hypotensiveepisodes are avoided intraoperatively so as to prevent possible cerebrovascular or cardiovascular crises 1 .Invasive arterial and venous pressuremonitoring is considered mandatory as excessive hemodynamic variations could have serious consequences for regional organ perfusion. However, pulmonary artery catheterization was not performed in view of the potential risks exceeding the possible benefits in a smallchild 1,3 .The factors affecting the transplanted kidney's viability are intravascular volume and perfusion pressure.Adequate intravascular volume is the single most important determinant of immediate graft function. ACVP of 12-14 mmHg is recommended to maintain optimalintravascular volume 8. Acute tubular necrosis can result from inadequate hydration and leads todelayed graftfunction, decreased graft survival and increased patient morbidity. Mannitol when combined with volume expansion has been shown to decrease the incidence of acute tubular necrosis after transplantation 9 .Routine use of inotropes is not warranted and vasopressors should be given as the last resort 3 . Unexplained hypotension and inadequateresponse toinotropes may be due to underlying metabolic acidosis and should be corrected. These patients warrant intensive care stay in post operative period. Our patient had stable haemodynamics during the intraoperative period probably due to a balanced anaesthetictechnique andCVP guidedvolume replacement.
Anaesthetisinga childwith Takayasu'sarteritis for an auto renal transplantation is a challenge due to the various pathological and hemodynamic changes involved. Successfuloutcome depends on preoperative optimisation, intra operative maintenance of stable hemodynam ics and invasive monitoring during perioperative period.